Process of making insulating-joints.



L. MCCARTHY.

PROCESS OF MAKING INSULATING JOINTS.

APPLICATION FILED JUNE I, 19m.

1 1 7 1 ,860 Patented Feb. 15, 1916.

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Zd/firaaiiaz' I /4 Java/17%: ywpfiw Zia/a wh cm PLANOORAPH co-. WASHINGTON D c LOUIS MCCARTHY, OF BOSTON, MASSACHUSETTS.

PROCESS 0F MAKING INSULATING-JOINTS.

Specification of Letters Patent.

Patented Feb. 15, 1916.

Application filed J une 1, 1914. Serial No. 842,008.

To all whom it may concern: 7

Be it known that I, LOUIS MCCARTHY, a citizen of the United States, lesldlilf at Boston, county of Suffolk, State of assachusetts, have invented a certain new and useful Improvement in Processes of Making Insulating-Joints, of which the following is a specification, reference being had therein to the accompanying drawings.

My invention has for its object a new and improved process of making insulators and particularly the insulating oint shown and described in a com anion application filed June 1, 1914, Ser. N 3). 842,007, to which reference may be had for a description of the structure, characteristics and mode of operation of the joint produced by the herein described novel process. This insulating joint belongs to the type comprising two end members and a shell composed of steel, said members being separated from each other by insulating material as will be described.

The particular object of the invention is to provide a process by which a joint employing mainly an insulating substance ca pable of being dry molded and having a flanged shell may be rapidly and economically made.

My improved process eliminates the tamping of the insulating material and produces an insulator having relatively great electrr cal and mechanical strength.

The invention will be fully understood by reference to the following description taken in connection with the accompanying drawings and the novel features thereof are particularly pointed out and distinctly defined in the claims at the close of this specification.

In the drawings, Figure 1 shows the steel shell; and Fig. 2 the lining tube of mica. Fig. 3 shows the shell and lining assembled. Fig. 4 shows the lining shaped to conform to the shape of the interior of the shell. Fig. 5 shows one of the end members. Fig. 6 shows the end member shown in Fig. 5 but with a block of insulating material molded about it. Fig. 7 shows the mica washer which is interposed between the proximate faces of the end members and masses of insulating material which are molded about the end members. Fig. 8 is a vertical section showing two of the end members assembled within the shell and mica lining with the mica washer interposed between their proximate faces. Fig. 9 shows the completed insulator. Fig. 10 is a vertical section of the completed insulator.

Referring now to the drawings, there is shown at 11 in Fig. 1 a shell made of steel or other suitable metal capable of being shaped in suitable dies. This shell is preferably non-cylindrical but I do not limit myself to this construction. At 12 (see Fig. 2) is shown a tubeformed of layers of mica, preferably constructed in the well known manner by superimposing leaves of mica coated with a suitable insulating adhesive such as shellac to form a sheet which is then rolled upon a mandrel to form a tube and is then cut into sections of suitable length. After the tube 12 has been formed, it is placed inside the steel shell 11, as shown in Fig. 3 and it is then expanded by means of a suitable expanding mandrel, said mandrel being heated to soften the insulating adhesive in the mica tube and to cause it to fit closely the interior of the shell and retain this shape. If the shell is non-cylindrical, the micatube is thus caused to assume a corresponding shape. The parts in this condition are shown in Fig. 4.

In Fig. 5 is shown one of the end members 13 having a screw threaded hole 14 bored in it and having a shoulder 15 preferably of non-circular shape formed thereon. These end members are placed in suitable dies and surrounded by a so-called dry insulating material in damp powdered condition and subjected to pressure in dies which mold the insulating material about the shoulder of the end member and forms a block 16 of insulating material. Various compounds suitable for this purpose are well known, to those skilled in the art, and consist primarily of silica, lime and clay or the like in suitable proportions. After the insulating compound has been molded about the end members as described, the parts, together with a washer 17 of insulating material (see Fig. 7) are assembled inside the shell, as shown in Fig. 8, and the whole placed in a suitable die by means of which the ends of the shell are shaped over the shoulders of the masses of insulating material on the end members and the shell is given the final shape as shown in Figs. 9 and 10. The edges of the shell are inturned or crimped while the blocks of insulating material are still capable of being molded and the heavy pressure to which the shell is submitted is transmitted to the insulating material so that it fills any minute irregularities caused by the folding of the shell.

t also densilies the insulating material and locks all the parts securely together. Thereafter the insulator is placed in an oven and baked, after which the completed insulator is thoroughly dried- The baking process expels all of themoisture and converts the insulating material into a hard stonelike substance having mechanical strength and good insulating properties.

The novel process described makes it possible to produce a commercially practical insulating joint employing a compound capable of dry molding, as the chief insulating medium. These insulating joints have the necessary mechanical strength and an electical resistance sutl'icient in small sizes to Withstand at least 5000 Volts between the end members and between the end member and the metal shell.

My process does away with the necessity for tamping the insulating material and makes it possible to employ this material in combination with a shell having inturned edges and end pieces having protruding flanges, this bein the strongest type of insulating joint known.

Wha I claim is:

l. The process of making an insulator which consists in dry molding about each of the end members successively an insulating material capable of being hardened by heat,

placing a tube composed of superposed leaves of mica Within a steel shell, assembling said end pieces about which has been molded said insulating material and a Washer of sheet mica separating them Within said shell anl tube of mica, compressing the edges, of the steel shell over the shoulders of the insulating material formed on the end members While the insulating material still capable of being formed and baking the insulator.

2. The process of making an insulator which consists in dry molding about each of the end members successively an insulating material capable of being hardened by heat, placing a tube composed of superposed leaves of mica Within a steel shell, expanding said tube of mica by ieat and pressure to cause it to conform to the interior oi said shell, assembling Within said shell and tube of mica the end pieces about which has been molded said insulating material and a Washer of sheet mica separating them, torming the steel shell while the insulating material is still capable o1 being formed, and subjecting the insulator to heat to harden the insulation about the end members.

In testimony whereof I atlix my signature, in presence of two Witnesses.

LQJUIS MCCARTHY. lVitnesses Errmn Soanmn,

W. Pnon'rr.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, 1). (1. 

